Control for oil burners



Oct. 11, 1932.

c. L. RAYFIELD 1,881,949

CONTROL FOR OIL BURNERS Original Filed Dec. 29, 1927 5 Sheets-Sheet lIE1 ar/es fl g 661d by PQIYE Oct. 11, 1932. c. L. RAYFIELD 1,881,949

CONTROL FOR OIL BURNERS Original Filed Dec. 29, 1927 3 Sheets-Sheet 2 B91 H k Oct. 11, 1932.

C. L. RAYFJELD CONTROL FOR OIL BURNERS Original Filed Dec. 29, 1927 3Sheets-Sheet 3 7/4 \MMHWWI ??1 5 11 i 11.?

Patented Oct. 11, 1932 UNITED STATES PATENT OFFICE CHARLES L. RAYFIELD,OF CHICAGO, ILLINOIS, ASSIGNOR TO RAYFIELD MANUFACTUR- ING 00., OFCHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS CONTROL FOR OIL BURNERSApplication filed December 29, 1927, Serial No. 243,361.

My invention pertains to a control for an oil burner and moreparticularly to a thermostatically operated mercury switch constructionfor controlling the operation of an oil burner.

The present invention relates to an oil burner of the same generalcharacter as that disclosed in my copending patent application? SerialNo. 219,652, filed September 15, 192

I propose in accordance with the features of my invention to provide anovel oil burner control adapted to automatically shut off the supply offuel should the jet of fuel being projected in the furnace fail toignite or should it go out after it has once been ignited and alsoadapted to automatically disconnect the spark unit from the operatingcircuit once the jet of fuel has been ignited or to again automaticallyimpose it in the circuit shouldthe burner go out.

An object of my invention is the provision of an improvedthermostatically operated oil burner control.

Another object of the invention is to provide a novel heat sensitivecontrol for a mercury switch adapted to control the operation of the oilburner motor.

Other objects and advantages of the present invention will more fullyappear from the following detailed description taken in connection withthe accompanying drawings which illustrate a single embodiment thereofand in which:

Figure 1 is a view of an oil burner partly in section showing the mannerin which my novel control is applied thereto;

Figure 2 is a diagrammatic view illustrating the electrical connectionsof my novel.

Renewed J'anuagy 18, 1932.

Figure 6 is a fragmentary vertical sectional view taken on substantiallythe line VI-VI of Figure 4 looking upwardly;

Figure 7 is a fragmentary sectional view taken on substantially the lineVII-VII of Figure 4 looking in the direction indicated by the arrows;and

Figure 8 is a fragmentary sectional view taken on substantially the lineVIII-VIII of Figure 4 looking in the direction indicated by the arrows.

In the drawings:

Like reference characters designate SIIXLlF lar parts throughout theseveral views.

In Figure 1 it will be observed that the reference character 10designates generally an oil burner including a discharge nozzle 11extending into a furnace 12. 'The burner 10 also includes an operatingmotor 13 and is mounted upon a bench or table 14. Associated with theoil burner 10 and mounted above the table 14 is a control mechanism 15embodying the features of the present invention. This control mechanism15 includes a switch box 16, a furnace thermostat 17 positioned withinthe furnace above the nozzle 11, and a flexible shaft 18 connected tothe thermostat 17 and extending into the switch box 16.

The switch box 16 includes a cover 19 (Figure 1) and a base 20 (Figure3). In Figure 3 the base 20 of the switch box is clearly shown and thecover 19 is omitted in order to show the switch mechanism mounted uponthe base 20. The base 20 may be attached in any suitable manner to thehousing of the oil burner 10 as shown in Fi re 1.

The thermostat 17 and the flexible shaft 18 connected thereto are of thesame construction as that disclosed in my copending patent applicationSerial No. 219,651, filed September 15, 1927. This thermostat 17includes a spiral strip 21 of thermostatic metal having a shape similarto that of a clock spring. The inner end 22 (Figure 5) of this strip 211s connected to one end of the flexible shaft 18. The outer end of thisstrip 21 is connected at 23 to an extension 24 formed integral with thehousing member 25 which includes a dent that the flexible shaft 18housed in a flexible conduit 27. 'The, other endjof the flexible shaft18 extends into the switch box 16 through a suitable opening in thecover 19 the shaft 18- (Figures 4 and 8) adjacent the bracket 28 are apair of complementary blocks 31 and 32 each of which has an arcuategroove 33 and 34. The two grooves 33 and 34 are disposed directlyopposite each other and are adapted to have fitted inthem the shaft 18(Figure 8). ,The block 32 may be made of any suitable insulation and jis resiliently clamped to the shaft 18" and to the block 31 by means ofa bolt 35, a. nut 36 threaded on an end of the bolt, and-a spring 37positioned between the nut andthe block 32. It will be observedfromFigure 8 that the bolt 35 extends clear through the blocks 32 and.33. Obviously, by adjusting. the nut- 36 on the bolt 35 it ispossible'to vary the tension on the spring 37, thus varying thepressureof the block 32 on the block Y31 and varying the gripping actionofthe'se blocks on the shaft The block 31 has formed integral with it alateral extending arm 38 which is positioned adjacent the bracket 28, asbest shown in Figures 4 and 8.v The free end of this arm extends betweenthe ears 3939 of a U- shaped member 40 secured to base 20. The legs39'39 of this member 40 carry adjusting screws 41 the-inner ends ofwhich are adapted to-contact the. arm 38 to limit its travel. Obviously,by adjusting the position of the adjusting screws 41-41, it-is possibleto vary the distance which the arm 38 can travel. Attention is directedto the fact that when the arm 38 strikes either of thesescrews the block31 can no longer travel with the shaft 18 should the shaft continue torotate. Now, due to the factthat the two blocks 31 and 32 areresiliently clamped to the shaft 18, it will necessarily follow thatafter the arm 38 has struck either of the sorews'41 the shaft 18 cancontinue to turn independently of the blocks. This is desirable for thereason that should the thermostatic strip 21 continue to expand afterthe arm 38 of the block 31 has moved as far as the stop screw willpermit, the shaft 18 may turn with the thermostat, thus preventing thethermostatic coil from being subjected to undue strains and stresseswhich would tend to distort it.

Also formed integral with the block 31 is a lateral extending arm 42(Figures 3 and 4) which projects in a direction opposite to that of thearm 38. This arm 42 is formed inte-- gral with one end of the block 31whereas the other arm 38 is formed integral with the other end of theblock. Threaded into the free .end of the arm 42 is an adjusting screw43 including a lock nut 44 threaded on an intermediate portion of thescrew. The purpose of this adjusting screw will be more fully explainedhereinafter.

Secured to the top of the block 31 is a plate 45 igure 8) which hasformed integral with 1t a pair of spaced U-shaped clips 46-46. Theseclips are adapted to resiliently embrace the wall of the cylindricallass tube 48 which is hermetically sealed at both ends. The tube 48contains a quantity of mercury 49. Positioned within the tube 48 anddisposed concentric with it is an inner glass tube 50 both ends of whichare formed open. This inner glass tube is spaced from the inner wall ofthe tube 48 by means of a ring of insulating material 51 which may becomposed of asbestos or any other suitable material. This ring, as shownin Figure 8, is positioned between the ends of the tubes and surroundsan intermediate portion of the inner glass tube 50.

Extending into one end of the tube 48 is a contact element 52 disposedin contact with the body of mercury 49. Extending into the other end ofthe tube 48 is a contact element 53 disposed in contact with anothermass of mercury 54. Also, it will be noted thata bent contact element 55extends into the top of the tube 48 and through an opening 56 in theinner tube 50 into the bore of this latter tube. The element 55 is atall times disposed in contact with the mass of mercury 49. When the tube48 is in the position shown in Figure tion of the tube48 is that shownin Figure 8.

This tube is tipped to its other position when the shaft 18 is turned bythe thermostatic strip 21.

In Figures 3 and 4 it will be observed that the tube 48 is properlyspaced from the bracket 28 by means of a spacing sleeve 57' surroundingthe portion of the shaft 18 in- I termediate the bracket 28 and theblocks 31 and 32. Also mounted upon the shaft 18 (Figure 7 is a solidmetallic block 58 whichis spaced from the blocks 31 and 32 by means of aspacing sleeve 59 (Figures 3 and 4) surrounding an intermediate portionof the shaft 18. This block 58 has mounted upon it a glass tube 60which, as will be more fully described hereinafter, houses a motorcontrol switch. The block 58 is spaced from the bracket 29 by means of aspacing sleeve 61 (Figures 3 and 4).

Secured to the top of the block 58 is a plate 66 which has formedintegral with it a pair of U-shaped clips 67 (Figure 7) adapted toresiliently embrace the glass tube 60. It is, of course, to beunderstood that the block 58 is loosely mounted upon the shaft 18whereas the blocks 31 and 32 are resiliently clamped to the shaft so asto rotate therewith. The shaft 18 extends through one end of the clock58 whereby the other end of the block is allowed to serve as acounterweight for tipping the tube, as will be more fully explainedhereinafter.

Mounted within the glass tube is an inner glass tube 68 spaced from theinner wall of the outer tube by means of an insulating washer 69 whichmay be made of asbestos or any other suitable insulating material. Bothends of the tube 60 are hermetically sealed whereas both ends of theinner glass tube 68 are formed open. Extending-into the ends of the tube60 are a pair of contact elements 71 and 72 adapted to contact through abody of mercury 70 disposed in the tubes. When the tube 60 is tipped tothe position shown in Figure 7 the two contacts 71 and 72 will beelectrically connected by the mercury 70. On the other hand, when thetube 60 is tipped to its other position the mercury 70 will flow intothe other end of the tube 60 through the inner glass tube 68. In. thislatter position the insulating washer 69 serves to separate the mercuryinto two separate bodies as is well-known to those familiar with thistype of mercury switch. I

Formed inte ral with the block is an extension or arm 3 which projectsin the path of a plunger 74 extending through an opening 75 in base 20(Figure 7). This plunger is rigidly fastened to one end of a collapsiblebellows 76 positioned in a casing 77 disposed on the outer side of thebase 20. Secured to the casing 77 and surrounding a portion of theplunger 74 is a nipple 78 threaded into the opening 75. A. small sleeve79 is threaded into the nipple 78 and surrounds the plunger 74, as shownin Figure 7. The other end of the bellows 76 has secured to it a smallsection of tubing 80 which extends outwardly through, an opening in thecasing 77. A nipple 82 surrounds this tubing 80 and is preferablythreaded so as to enable it to be connected to a suitable air line suchas the source of compressed air used in connection with the conventionaltype of oil burner.

Now, when the pressure in the air system connected to the bellows 76reaches a predetermined degree the plunger 7 4 will be pro-. jected intothe path of the arm 73 whereby the tube 60 will be held in the positionshown in Figure 7. When in this position the contacts 71 and 72 areelectrically connected ghrough the means of the body of mercury Theblock 58 also has formed integral with it a lateral extending arm 83(Figures 3 and 4) positioned over the arm 42 of block 31. This arm isadapted to-be engaged by the screw 43 of arm 42 previously described.Obviously, if the arm 42 is moved upwardly through the movement of theblock 31 by shaft 18 it must necessarily follow that when the screw 43strikes the arm 83 the tube will be tilted about the axis of shaft 18.tilted position of the tube 60 is shown in Figure 7 and is the positionin which the tube is in at the time the burneris set in operation. Thisscrew adjustment permits the tube 48, which is the spark control tube,to operate slightly ahead of tube 60, which is a motor control tube, sothat the spark ignition will be on when the motor starts. Thecounterweight block 58 is adapted to move the tube 60 downwardly shouldthe plunger 74 be moved out of the path of its arm 73.

Connected to the base 20 is a pivot pin 85 upon which is pivotallymounted a lever-like member 86. Rigidly fastened to this member 86 is aplate 87 which has formed integral with it a pair of U-shaped clips 88ada ted to receive and embrace a glass tube 90. ISO mounted upon themember 86 and extending through the U-shaped clips 8888 is a tube 91secured at its ends by means of bolts 92 to the ends of member 86.Disposed in this tube 91 are a plurality of balls 93. These ballsareheld within the tube bymeans of the bolts 92 which extend through theends of the tube and thus constitute closures for the ends of the tube.These balls insure that the member 86 is maintained in one or the otherof its extreme two tilted positions.

The glass tube is hermetically sealed at both ends and has extendinginto it a pair of contact elements 94 and 95. Disposed within the glasstube 90 is an inner glass tube 96 having both of its ends formed open.This inner tube 96 is spaced from the outer tube by means of a washer 97made of asbestos or other suitable insulating material. Disposed Thiswithin the tube are two bodies of mercury 1 89 and 98. These bodies ofmercury are shown in Figure 6 as being held out of con tact by means ofthe washer 97. However, it is to be understood that when the tube 90 isin its normal tilted position, which is the reverse of that shown inFigure 6, the contacts 94 and will be electrically connected the tube90. The other end of the member 86 is adapted when the member is tiltedto its reverse position from that-shown in Figure 6 to strike a stop pin102 secured to the base 20.

Also connected to the base is a pivot pin 103 upon which is pivotallymounted an angular member 104 including a vertical leg 105 and ahorizontal leg 106. Secured to the leg 106 is one end of a thermostaticstrip of metal 107. The other end of this strip has secured to it avertical stud 108 adapted when the thermostatic strip 107 expands tostrike the end of the member 86 adjacent pin 102 and to thus move themember 86 and the tube 90 to the tilted position shown in Figure 6.

Secured to an intermediate portion of the strip 107 by means of a boltand nut 109 is an electrical resistance coil 110 which, as

will be more fully explained hereinafter, is connected to the sparkcontrol tube 48.

The other leg 105 of member 104 has s e cured to it one end of athermostatic strip 111 the upper end of which is forked as indicated at112 so as to straddle the shank of an adjusting bolt 113 which isthreaded into a lug 114 formed integral with base 20. The

bi u

rcated end 112 of strip 111 is disposed between tlTe' head 115 of thebolt and a shoulder 116 formed integral with the bolt. This strip 111 isresponsive to changes in atmospheric temperature and is adapted toexpand in a reversed direction tothat of the strip 107 wherebycompensation is made for any variation in room temperature.

Secured to the front of the base 20 is a terminal strip 120 to which arefastened eight terminals 121, 122, 123, 124, 125, 126 127, and 128(Figure 3). I shall now proceed to describe in detail the circuitassociated with my novel control mechanism.

In Figure 2, in order to simplify the explanation ofv the presentinvention, I have illustrated the circuit and the parts connectedthereto in a. diagrammatic manner.

Connected to the terminals 121 and 122 are power leads 129 and 130 whichmay be connected to any suitable source, such, for example, as a 110volt line. The terminal 121 is also connected by a wire 131 to-one endof the resistance coil 110. The other end of the resistance coil 110 isconnected by a con,-

' ductor 132"to the terminal 123. The contact 94 of tube 90 is connectedby a conductor 133 to terminal 122. The contact 95 of tube 90 isconnected to terminal 124 by means of conductorv 134. The terminal 121is also connected to the terminal 128 by means of a strap wire 135.

The motor 13' of the oil burner is connected to the terminals 123 and125'by means of leads 136 and 137, respectively. Contacts 71 and 72 oftube 60 are connected to terminals 124 and 125, respectively, by meansof leads 138 and 139. The terminal 123 is connected by a strap wire 140to terminal 127. Gontacts 52 and of tube 48 are connected to terminals126 and 127, respectively, by means of conductors 141and 142. The othercontact 53 of this'tube is connected to terminal 128 by means of aconductor 143.

The spark plug used in conjunction with the control of the oil burner isalso shown diagrammatically in Figure 2 and is designated generally bythe reference character 145. Theplug is connected by leads 146 and 147to the secondary winding 148 of a transformer 150. The primary winding149 of this transformer is connected by leads 151 and 152 to terminals125 and 126, respectively. The conductor 151 is connected to theterminal 125 through the conductor 137, as shown in Figure 2.

The operation of my novel oil burner control is, briefly, as follows:

The first thing to be done is to make sure that the tube 90 is properlyset. This is done by operating the reset lever 100 (Figure 6) whichcauses the tube to be tilted until the member 86 strikes the pin 102.This results in the contacts 94 and 95 being connected through the bodyof mercury 89.

Now, normally when the oil burner is in an inoperative osition thethermostat 17 will maintain the s aft 18 in such a position as to holdthe tubes 48 and in the positions shown in Figures 8 and 7. Of course,it will be evident that the cooling or contraction of thermostat 17results in the rotation of shaft 18, thus causing tube 48 to be moved toits normal position shown in Figure 8. Obviously this tube 48 in movingwith shaft .18 will, through its arm42, move tube 60 to the positionshown in Figure 7. In fact, it is the contracted thermostat itself whichmaintains the two tubes 48 and 60 in their normal positions prior to theoperation of the oil burner. When the tube 48 is in this position thecontact element 52 is connected to the contact element 55. Moreover,when the tube 60 is in this position the contact element 71 is connectedto the contact element 72 (Figure Upon the source of power beingconnected to leads 129 and 130, current flows through the resistancecoil 110 to heat the same so as to bend it, the motor 13, and the threetubes 90, 60, and 48. It is to be understood that in order for the motorto operate both of the switches housed in tubes 90 and 60 must be intheir closed positions. If either of these mercury switches is brokenthe motor will be rendered inoperative. Obviously, the operation of themotor results in the operation of the compressor unit (not shown) of theoil burner proper. As a result of the operation of the; compressor unitthe pressure in the air line connected to the bellows 76 (Figure 7) isincreased to a suflicient degree to cause the plunger to be projected inthe path of the arm 73, thus holding the tube 60in the position shown inFigure 7. It is to be noted that this plunger is normally actuatedbefore the thermostat has been heated and hence before tube 48 has beenmoved from its normal position. 5 Therefore, it is apparent that the arm42 of tube 48 will have prevented tube 60 from gravitating to its lowerposition.

a Current from the power leads 129 and 130 also flows through themercury in tube 48 connecting contact elements 52 and 55 and through thetransformer-150. This results in a spark being emitted by the spark plug145, thus igniting the charge being pro] ected into the furnace 12.

If the charge of fuel leaving the nozzle 11 of the oil burner is ignitedit will result in the heating of the thermostatic coil 17. This coilupon being heated turns in a direction away from extension 24 (Figures 4and 5), thus revolving shaft 18 and moving tube 48 to a position whereinthe contact elements 52 and 55 are disconnected and the contact elements53 and 55 are electrically connected. As a result of this movement ofthe tube 48 the transformer 150 is disconnected from the circuit wherebythe spark plug 145' will be deenergized. Also, this movement of the tuberesults in the current flow through the resistance coil 110 beingdiminished due to the closing of a shunt circuit. It must be understoodthat all of the above described action takes place in a relatively shorttime so that the coil 110 is not heated to a sufficient degree todisplace the thermostatic strip 107 laterall l n the event that thethermostatic coil 17 is not heated to a suflicient degree to actuate theshaft 18 before the resistance coil 110 is heated, this coil willoperate to move the strip 107 (Figures 2 and 6) upwardly whereby theblock 86 and the tube 90 are moved to the position shown in Figure 6. Asa resultof this movement of tube 90 the mercury switch therein isopened, thus disconnecting contacts 94 and 95- and breaking the motorcircuit whereby the motor will be'rendered inoperative. This isadvantageous for the reason that it prevents fuel or oil from beingdischarged into the furnace when the burner has not been ignited, thusgreatly reducing the possibility of a fire or explosion. Obviously, ifthe motor is rendered inoperative the pressure in the'air system willdrop and as a result the sylphon 76 will contract, thus withdrawing theplunger 74 out of the path of the arm 73.

If during the operation of the oil burner the thermostatic strip 17should be suddenly cooled to a suflicient degree to return the tube 48to the position shown in Figure 8 the current will again flow in theresistance coil 110. When the current has heated the coil to a givendegree it will move the tube 90 to the position shown in Figure 6, aspreviously de- 05 scribed, thus rendering the motor inoperative.

Now it will be understood that if the air pressure in the compressorunit system of the burner connected to bellows 76 should at any timefail during the operation of the burner the plunger 74 will be withdrawnout of the path of the arm 73 and the tube 60 will drop to its lowerposition wherein the contact elements 71 and 72 will be disconnected,thus rendering the motor inoperative. Thereafter the gradual cooling ofthe furnace thermostat will result in the turning of the shaft 18, thuscausing the two tubes 48 and 60 to be moved back to the positions shownin Figures 7 and 8, namely the starting positions of these tubes. Duringthis movement of tube 48 the arm 42 through its screw 43 contacts thearm 83 connecting the tube 60 and returns tube 60 to its normalposition, thus placing the motor in a condition to be operated. Thisscrew adjustment allows the con tacts 52 and 55 of tube 48 to beconnected slightly ahead of the contacts 71 and 72 of tube 60 so'thatthe spark will be on when the motor starts. The screw 43 is adjustableto vary the time in which the tube ,60 will be returned to its normalposition by the tube 48.

As previously described, the thermostatic strip 111 is responsive tochanges in atmospheric temperature and is adapted to compensate for anychange in the thermostatic strip 107 due to variation in atmospherictemperature. In other words, the strip 111 is set to flex in an oppositedirection from the strip 107 (Figure 6) and inasmuch as these twometallic strips are joined together the strip 111 must of necessitycompensate for any variation in the strip 107. The time of operation ofthe switch operating strip 107 can be varied by moving the thermostaticmetal strip 111 forward or back thru the means of the adjusting screw113. For example, if the switch operating strip 107 is set to functionfor two minutes in a room where the temperature is 80 F. and the roomtemperature should be lowered to say 50, it will mercury switch in tube90 in two minutes.

Now I desire it understood that although I have illustrated anddescribed in detail the preferred form of my invention, the invention isnot to be thus limited, but only in so far as defined by the scope andspirit of the appended claim. 4

-I claim as my invention:

In combination, an oil'burner, a 'motor for operating the same having apower circuit, an electrically operated time limit cut-ofi' in saidpower circuit to deenergize the motor on ignition or combustion failure,an electric igniter; a thermostat positioned to be heated by the burner,a switch device operable there'- by electrically connected to saidigniter and said time limit cut off to operatively deenergize the samewhen said thermostat is heated, an eocentrically pivoted switch in saidpower 'be found that this strip will still operate the circuitmechanically connected to said first switch to be held in closedposition thereby when said thermostat is cold and to be released foropening movement when said ther- 5 mostat it hot, and a device operableby the pressure of air fed to the burner during burner operation tomaintain said pivoted switch in closed position.

In testimonyv whereof I have hereunto sub- 10 scribed my name atChicago, Cook county,

CHARLES L. RAYFIELD.

